Thread severing device for sewing machines



Aug. 19, 1947. A. p. KEHRER THREAD SEVERING DEVICE FOR SEWING MACHINES Filed April 20, 1945 flrroelvay I Patented Aug. 19, 1947 UNITED STATES ATENT OFFICE THREAD SEVERIN G DEVICE FOR SEW'IN G MACHINES 8 Claims.

My invention relates to a thread cutting device for sewing machines, and more particularly to an attachment which can be so located and operated as to sever the stitching closely adjacent to the edge of the work.

Most devices of the prior art provide for mechanisms which comprise various cutting devices which shear the stitching, and embody various moving members which must be coordinated and operable together to sever the stitching. These devices are more or less complicated and require Various mechanisms which must be coordinated in operation and constructed to relatively close limits.

It is an object of my present invention to overcome the aforesaid difficulties by providing a device which operates simply by gravity, and which is preferably constructed and arranged. to be attached to a standard sewing machine, and which comprises a single cutting blade which serves as the sole cutting medium and is not ordinated with any other moving parts of the sewing machine.

For a more detailed understanding of my invention, reference may be had to the accompanying drawing which illustrates one form which my invention may assume, and in which:

Fig. 1 is a side elevational view of part of the sewing machine and showing my cutting device assembled therewith,

Fig. 2 is a fragmentary sectional view showing the cutting device elevated and taken substantially on the line 2-2 of Fig. 4,

Fig. 3 is a similar fragmentary sectional view showing the cutting device lowered by gravity into cutting relation with the thread or stitching,

Fig. 4 is a plan sectional view thereof taken substantially on the line fi4 of Fig. 2, and

Fig. 5 is a perspective view of a modified construction.

The sewing machine is of any standard construction and preferably includes a stitching head Iii provided with the usual form of reciprocating stitching mechanism, H, a serrated work feed bar I 2, and a pressure foot l3. A bracket I4 is secured to a rigid portion of the sewing machine and in this instance, to the stitching head l E], said bracket being provided with down turned ears l5, that carry a shaft or pintle it, which pivotally supports the thread cutting device 2%.

This thread cutting device comprises rounded shoe arms 2| and Zia which are spaced apart and connected by an intermediate bridge portion 22. The under side of the bridge portion 22 is recessed as at 23 and the knife blade Ed is clamped to the under side of said bridge portion 22 by a plate 25 by means of the screw 26 or other suitable securing means.

The work W is fed through the sewing machine and stitched in the usual manner, and 1 preferably provide a pair of cooperating pres,-v sure rolls 38 at the rear of the sewing machine, which frictionally engage the work to pull same over a work support SI secured to the bed 32 of the sewing machine. It is necessary to provide this supplemental work feeding mechanism because as the edge 33 of the work passes beyond the influence of the work feeding mechanism of the sewing machine, it would not be forced or pulled through the thread cutting device. These pressure rolls insure the feeding of the work over the work support 3 l The work support provides a relatively smooth work supporting surface 33 and is provided with recesses 3 and 34a aligned with the shoes 2| and 2 ta for cooperating relation therewith. The work W bridges these recesses and serves to support the shoes 25 and 2m in such a way as to elevate the knife above the work. Immediately when the edge of the work passes out from under these shoes 2! and 21a, the cutting device is permitted to be lowered by gravity, these shoes being permitted to enter the recesses 34 and 34a. The knife is permitted to thus fall toward the intermediate work supporting portion 35 and it will be observed that the stitching is supported on this intermediate surface and when the knife is lowered into cutting relation therewith, the pull on the work will draw the thread toward or against the cutting edge of the knife blade and thus the thread will be severed at a point closely adjacent to the edge of the work.

Fig. 5 shows a modified construction which functions in a manner substantially like the device illustrated in Figs. 1 and 4 inclusive. Refer-ring more particularly to Fig. 5, the cutting device 29 is hinged to bracket M at l6, and carries spaced shoe arms 2i and 21a and an intermediate knife blade 24, which are operable in a manner substantially identical with shoe arms 21 and 2m, and knife blade 24 of the preferred construction shown in Figs. 1 to 4 inclusive. It will be apparent to those skilled in the art to which my invention pertains, that various modifications and changes may be made therein without departing from the spirit of my inven tion or from the scope of the appended claims.

I claim:

1. A thread cutting device for a sewing machine, a work support, work feeding mechanism including means frictionally engaging the work to pull same over said work support after same passes beyond the sewing machine work feeding mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said device supported by said work to elevate the knife blade above said work, said device comprising a knife blade support constructed to position the knife blade at an acute angle to the work with the sharp edge thereof extending in opposed relation to the travel of the work, said device being free to fall by gravity on passing of said work from under said device to lower the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work.

2. A thread cutting device for a sewing machine, a work support fixed to said machine to the rear of the sewing machine work feeding mechanism and stitching mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said work support having a recess to one side of the line of stitching and in which said device may enter, said work in passing over said work support being positioned to overlie said recess and support said device in an elevated position to elevate the knife blade above said work, said device constructed and arranged to be lowered by gravity into said recess as the work is passed beyond said recess to thereby bring the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work.

3. A thread cutting device for a sewing machine, a work support fixed to said machine to the rear of the sewing machine work feeding mechanism and stitching mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said work support having a recess to one side of the line of stitching and in which said device may enter, said work in passing over said work support being positioned to overlie said recess and support said device in an elevated position to elevate the knife blade above said work, said device constructed and arranged to be lowered by gravity at least partially into said recess as the work is passed beyond said recess to thereby bring the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work, said work support presenting a smooth surface over which said work passes, said knife operable to sever the stitching positioned to lie on said smooth surface of said work support.

4. A thread cutting device for a sewing machine, a work support fixed to said machine to the rear of the sewing machine work feeding mechanism and stitching mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said work support having a recess to one side of the line of stitching and in which said device may enter, said work in passing over said Work support being positioned to overlie said recess and support said device in an elevated position to elevate the knife blade above said work, said device constructed and arranged to be lowered by gravity into said recess as the work is passed beyond said recess to thereby bring the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work, said work support presenting a smooth surface over which said work passes, said knife operable to sever the stitching while positioned to lie on said smooth surface of said work support, said recess comprising a pair of recesses lying on opposite sides of the intermediate smooth surface of said work support coacting with the knife to sever the stitching.

5. A thread cutting device for a sewing machine, a Work support fixed to said machine to the rear of the sewing machine work feeding mechanism and stitching mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said work support having a recess to one side of the line of stitching and in which said device may enter, said work in passing over said work support being positioned to overlie said recess and support said device in an elevated position to elevate the knife blade above said work, said device constructed and arranged to be lowered by gravity into said recess as the work is passed beyond said recess to thereby bring the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work, said work support presenting a smooth surface over which said work passes, said knife operable to sever the stitching positioned to lie on said smooth surface of said work support, said recess comprising a pair of recesses lying on opposite sides of the intermediate smooth surface of said work support coacting with the knife to sever the stitching, said device comprising rounded spaced shoe arms resting on said work 'and an intermediate knife blade holding support substantially straddling the intermediate smooth work supporting surface of said work support.

6. A thread cutting device for a sewing machine, a work support fixed to said machine to the rear of the sewing machine work feeding mechanism and stitching mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said work support having a recess to one side of the line of stitching and in which said device may enter, said work in passing over said work support being positioned to overlie said recess and support said device in an elevated position to elevate the knife blade above said work, said device constructed and arranged to be lowered by gravity at least partially into said recess as the work is passed beyond said recess to thereby bring the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work, said work support presenting a smooth surface over which said work passes, said knife operable to sever the stitching positioned to lie on the smooth surface of said work support, said recess comprising a pair of recesses lying on opposite sides of the intermediate smooth surface of said work support coacting with the knife to sever the stitching, said device comprising rounded spaced shoe arms resting on said work and an intermediate knife blade holding support substantially straddling the intermediate smooth work supporting surface of said work support, a bracket secured to said sewing machine and pivotally supporting said device in proximity to said work.

'7. A thread cutting device for a sewing ma-- chine, a work support fixed to said machine to the rear of the sewing machine work feeding mechanism and stitching mechanism, means pivotally supporting said thread cutting device, a knife blade carried by said device, said work support having a recess to one side'of the line of stitching and in which said device may enter, said work in passing over said work support being positioned to overlie said recess and support said device in an elevated position to elevate the knife blade above said work, said device constructed and arranged to be lowered by gravity at least partially into said recess as the work is passed beyond said recess to thereby bring the cutting edge of said knife into cutting relation with the stitching adjacent to the edge of the work, said work support presenting a smooth surface over which said work passes, said knife operable to sever the stitching positioned to lie on said smooth surface of said work support, said knife blade being so constructed and arranged as to position the cutting edge of said knife blade so that the thread to be severed is pulled toward same, said knife blade positioned at an acute angle with respect to said smooth surface of said work support.

8. A thread cutting device for a sewing machine, a work support, work feeding mechanism including means frictionally engaging the work to pull same over said work support after same passes beyond the sewing machine work feeding mechanism, means pivotally supporting said thread cutting device, said device comprising a knife blade holder, a knife blade secured to said AGNES D. KEI-IRER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,293,236 Anderson Aug. 18, 1942 2,318,843 Enos May 11, 1943 

